which automatically kills non-responding apps instantly without interrupting the shutdown process. Before attempting this hack, please have a backup of your registry, just in-case something gets screwed up.
1.Open Registry Editor from Start > Run and type “regedit” (without quotes)
2.Expand the Registry Editor Tree and find HKEY_CURRENT_USER\Control Panel\Desktop
3.Edit AutoEndTasks Key from the right pane and assign to value to 1 (by default the value is 0)
Now, if you want to revert it back, just re-assign the value of AutoEndTasks Key to 0 or simple delete that key. Apart from the above hack, you can improve the shutdown/bootup speed by disabling unwanted service.